The summers in Houston, Texas, are grotesquely hot and sticky -- too hot to play or watch baseball. But in 1965, Judge Roy Hofheinz, the owner of the Houston Astros, found a way to do the impossible: play baseball in air-conditioned comfort. It was Hofheinz's idea to build a gigantic dome, large enough to cover a baseball field and grandstands for 50,000 people without a single column obstructing the players' or the spectators' view. The Houston Astrodome was the first ballpark in the world to have a roof over its playing field. Upon its completion, Judge Hofheinz dubbed his creation "the Eighth Wonder of the World." But there were problems with indoor baseball that no one had ever anticipated.

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The 4,007 skylights in the Astrodome acted like a lens, smearing the sun into a blinding wall of light. It was almost impossible to catch a fly ball! Work crews painted the skylights to block the sun, but then the grass died from lack of sunlight. This led to the installation of plastic grass, which later came to be known as Astroturf. From then on, generations of ballplayers complained about the Astroturf ruining their knees.

Less than two decades after the Astrodome was built, a revolutionary new design led to the introduction of the retractable domed roof. Domes with retractable roofs gave players and spectators the best of both worlds: the ability to play in air-conditioned comfort when necessary and under the open sky when possible. By the 1990s, the Houston Astros and their spectators were longing for their own retractable roof.

The Astrodome lasted just 35 years as a working ballpark. On March 30, 2000, the Astros began playing in Enron Field, their new retractable-roof stadium.

Here's how this dome stacks up against some of the biggest domes in the world.
(diameter, in feet)

Astrodome710'

Fast Facts:

During the 1965 season, the New York Mets claimed that the groundskeepers were manipulating the air-conditioning system by using air currents to help the Astros' longballs and hinder visitors' homers.

On June 10, 1974, the Philadelphia Phillies' Mike Schmidt hit a public-address speaker 117 feet above and 329 feet away from home plate. His hit could have been a 500-plus-foot homer, but it ended up a single because the ball dropped in center field.

On June 15, 1976, a game was rained out because the Astrodome flooded.